1. Field of the Invention
The present invention relates to a fluid filter, a drain mechanism thereof, a draining jig used in the fluid filter and a draining method of the fluid filter. The present invention more particularly relates to a fluid filter, a drain mechanism thereof, a draining jig used in the fluid filter and a draining method of the fluid filter, in which a heated fluid is not splashed on a worker at a time of discharging the fluid such as a time of exchanging an element, and can maintain a high reliability in sealing a drain hole for a long time period while inhibiting dusts or the like from being mixed from an external portion at a time of normal use.
The present invention can be widely used, for example, in an oil filter for filtering foreign materials, abraded powders, carbon and the like mixed in an oil lubricating an internal combustion engine, a fuel filter and a field relevant thereto.
2. Description of Prior Art
Conventionally, as a fluid filter, there has been generally known, for example, an element replacement type fluid filter in which a filter element is replaced at a time when a filter media is clogged after a predetermined time has passed and reaches a service life.
As a drain mechanism of the element replacement type fluid filter, there has been known, for example, a structure in which a drain member (a drain plug 15) is screwed with a drain hole formed in a cap (a lower case 12) (refer to a patent document 1). Accordingly, it is possible to detach the drain member from the drain hole by loosening the drain member so as to leave open the drain hole prior to separating the case and the cap by canceling the engagement between both the elements, thereby discharging a residual oil in an inner portion of the housing from the drain hole.
In this case, in the fluid filter for filtering an engine oil for a vehicle, an engine is frequently warmed up at a time of replacing the filter element, and the oil is in a heated state.
However, in the conventional drain mechanism, discharging the residual oil at a time of replacing the filter element is performed by detaching the drain member from the cap. In other words, at the same time when the drain member is loosened, and a sealing of a seal member (a packing 15a) for the drain member is cancelled, discharging the residual oil is started. As a result, there is generated a disadvantage that the heated residual oil overflows during a detaching operation of the drain member, and is splashed on hands of the worker.
Consequently, as the conventional drain mechanism of the fluid filter for solving the problem mentioned above, there has been known, for example, a structure in which a tubular drain pipe member (a drain plug 15) having a drain passage (a center hole 15g and a window hole 15f) is screwed with a drain hole formed in a cap (a lower case 12) (refer to a patent document 2).
The drain passage of the drain pipe member and the inner portion of the housing are sealed by a pair of seal members (the packing 15g) attached to an outer periphery of the drain pipe member, at a time of normally using the fluid filter. Further, when replacing the filter element, the sealing of the upper seal member is cancelled by loosening the drain pipe member, the drain passage of the drain pipe member and the inner portion of the housing are communicated with each other, and the residual oil within the housing is discharged via the drain passage.
Since the residual oil is discharged via the drain passage of the drain pipe member in the manner mentioned above, it is possible to prevent the oil in the middle of the discharging from being splashed on the hands of the worker.
In this case, when the seal of the upper seal member is cancelled by loosening the drain pipe member, the seal of the lower seal member is maintained, so that the residual oil does not leak out from the other portions than the drain passage of the drain pipe member at a time of discharging the residual oil.
Patent Document 1
Japanese Unexamined Patent Publication No. 2000-42309
Patent Document 2
Japanese Unexamined Patent Publication No. 11-104408
However, in the drain mechanism of the conventional fluid filter, since the drain pipe member is formed in the hollow shape and is structured such as to have the drain passage, dusts or the like such as sediments or mud or the like is mixed into the inner portion of the cap through the drain passage of the drain pipe member from the external portion, during a normal use of the fluid filter, so that it is hard to secure a reliability of seal in the drain hole achieved by the seal member.